I tested the impact of page speed on ads about 3 years ago. The CTR impact was pretty dramatic - I can't recall the exact numbers but they were in the order of

I tested the impact of page speed on ads about 3 years ago. The CTR impact was pretty dramatic - I can't recall the exact numbers but they were in the order of 50% CTR drop with 500ms delay. That's obviously specific to ads, but there's clearly still some impact from page speed there.